1. Field of the Invention
The present invention relates to the methods for preparing sesamin and sesamolin, and more particularly, to a method for preparing highly purified sesamin and sesamolin.
2. Description of Related Art
Since the ancient times, sesame has always been regarded as an elixir of health regimens. According to the disclosure of Shen Nong's Herbal Classic, sesame is beneficial to immunization, muscle and brain development, and long-term intake of sesame can lead to rejuvenesce and longevity.
Moreover, it is found from the results obtained from scientific studies conducted in recent years that sesame contains sesamin and sesamolin which have numerous beneficial physiological activities, such as anti-oxidation activity, increasing tocopherol content in vivo, increasing oil metabolism, lowering cholesterol content, prevention of hypertension, improving liver functions and prevention of cancer diseases. These studies showed that sesamin and sesamolin have high applicability in health foods and medicine-related fields.
Although recently some methods for preparing sesamin and sesamolin have been reported, these methods still cannot meet industrial demands in terms of the operating convenience or product purity. For example, U.S. Pat. No. 5,209,826, issued on May 11, 1993, discloses a method for separating sesamin and episesamin, comprising the steps of steam stripping, methylesterification and molecular distillation. However, the separating method requires not only to use expensive equipments, but also to perform a treatment at a temperature as high as 270° C. The product obtained is very prone to quality deterioration. Further, as shown in results of Test 4, the recovery rate of the product was only about 68%, and the purity of the product was only 85%.
Moreover, U.S. Pat. No. 5,902,458, issued on May 11, 1999, discloses a method of separating sesamin and episesamin, comprising the step of steam stripping. In addition, the separating method must, in the presence of an alkali, form precipitate in a solution of water and ethanol for separation. The recovery rate of the product obtained by the method only ranged from 65% to 85%. Further, the method uses a large amount of alkali, which can easily cause contaminations to the environment.
Furthermore, U.S. Pat. No. 6,278,005B1, issued on Aug. 21, 2001, discloses a method for concentrating the concentration of sesamin in sesame oil by using supercritical carbon dioxide. Nevertheless, the goal of the method is only the preparation of sesame oil containing a high concentration of sesamin, instead of preparing sesamin and sesamolin. Further, the method not only uses expensive equipments, but also obtains a total concentration of sesamin and sesamolin of only between 3 to 4%.
Additionally, CN1535970A, published on Oct. 13, 2009, discloses an art for extracting sesamin, comprising the steps of passing sesame oil through neutral aluminum oxide in a cylindrical container, using a fat-soluble solvent to elute oil impurities, collecting a color band containing sesamin from the center of the cylindrical container, and then using a solvent that dissolves sesamin to extract the sesamin from the color band. However, the amounts of the adsorbent and the fat-soluble solvent used by the method are very large. For example, the results in example 2 shows that the ratio of the amounts of the sesame oil and the neutral aluminum oxide used was 1:1, and the amount of the fat-soluble solvent used was 8 to 12 times more than that of the sesame oil (calculated on the basis that the milliliters of eluate obtained in 1 to 1.5 hour is equivalent to the milligrams of the neutral aluminum oxide and the total eluting time of 12 hours). Moreover, the recovery rate of sesamin was only 78.5%, and the method requires performance of the following steps during the operating period: cutting a piece of the neutral aluminum oxide from the center of the cylindrical container, and using >70% ethanol to extract sesamin by performing reflux. The cutting step stops the continuity of operation, which in turn causes inconvenience to operation and lowers the work efficiency. Further, the cutting step is likely to contaminate the work environment by causing solvents to easily evaporate, thereby being detrimental to human health.
In conclusion, an urgent issue of the industry recently to be resolved is to provide a convenient and efficient method for preparing sesamin and sesamolin with high recovery rates and high purity.